Application of anisotropy borehole radar tomography in korea

Although the main geology of Korea consists of granite and gneiss, it is not uncommon to encounter the anisotropy phenomena in crosshole radar tomography even when the basement is crystalline rock. To solve the anisotropy problem, we have developed the anisotropic inversion algorithm assuming the heterogeneous elliptic anisotropy to reconstruct three kinds of tomograms; tomograms of maximum and minimum velocities, and of the direction of the symmetry axis. In this paper, we introduce some case histories on the application of anisotropic radar tomography in Korea. The first two case histories were conducted for the constructions of infrastructures, and their main objective was to locate cavities in limestone. And last two were performed at granite and gneiss area. The anisotropy in granite area was caused by fine fissures aligned in the same direction, while that in gneiss and limestone area by the alignment of constituent minerals. Through these case histories, we want to show that anisotropic characteristic itself gives us additional important information for understanding the internal status of basement rock, when the subsurface material is anisotropic.